Method for controlling plant growth



United States Patent 3,285,730 METHOD FOR CONTROLLING PLANT GROWTH Konrad Weis, Willi Hahn, and Ludwig Elie, Cologne- Stammheim, Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverknsen, Germany, a German corporation No Drawing. Filed Mar. 11, 1963, Ser. No. 264,067 Claims priority, applicgtiog 2Geirmany, Mar. 15, 1962,

9 Claims. (in. 71-23 It has been :found that aromatic amines containing th-iocylano groups of the formula NEG-S R in which:

R stands for hydrogen, alkyl, halogen, nitro', hydroxy, alkoxy, alkylrnercapto, carboxyl and ester groups,

n stands for a Whole number from 1 to 2 and R' stands for hydrogen, alkyl, optionally substituted aryl and the radicals COR", COOR"' and RIV O O-N wherein R" and R stand for alkyl, chloroalkyl and optionally substituted aryl and R and R stand for hydrogen and alkyl wherein R" and R' stand for alkyl radicals with 1 to 4 carbon atoms, chloroalkyl radicals with 1 to 4 carbon atoms and the phenyl radical and wherein R and R stand for hydrogen and alkyl radicals with 1 to 4 carbon atoms.

The ifiollowing compounds may be mentioned as some examples of active representatives of this class of substances.

NO S N(CH:4)2

No s N\ COG/H Patented Nov. 15, 1966 Cz s ooNH-on, Cl

NC S@-NH-C o CHzCl 01 NC S-QNH-COGH; 01

NO s-Qnnooon, 01

O 0 011201 Cl No s -N/ oomon 01 NC SQ-NH-CONH-CH;

NOS-QNWHQ:

01 NO s-GNH:

No s-Qmonn):

OCH;

NC S NH:

NH-C O-O 01115 NGS- NOS-

NC 8- N(C a):

CH; OH;

The compounds to be employed according to the invention have in part been described in the literature or if they are unknown they can also be prepared quite generally according to methods known per se. Such methods have inter alia, been described in Houben Weyl, vol. 9, p. 859-865.

The mechanism via the thiocyanate introduction into aromatic amines according to the methods of P. Kaufma-nn (cf. summary in Ang. Chem. 54, 195 (1941)) has proved to be of particular advantage for the preparation. During this operation, it is possible either to introduce thiocyanate into an appropriately substituted aromatic amine or to introduce further substituents into an amine which has already been substituted by thiocyanate. The latter method is particularly suitable for the production 01f N-acylated thiocyano-amines and may be demonstrated by the example of N-ethyl-N(2-chloro-4-thiocyanophenyl) -N, N-dimethyl-urea:

N-ethyl-Z-chloraniline is substituted with thiocyanate by a method known per se according to Kaufmann. The N-ethyl-4-thiocyano-2-chloroaniline thus obtainable with good yields isthen converted to the tetrasubstituted urea either by reaction with dimethylcarbamic acid chloride in the presence of acid-binding agents or by reaction with chlorocar-bonric acid ester and subsequent amidation with dimethylamine.

Among the multiplicity of processes for the preparation, mention should also be made of the exchange of varieties hard 2-3 leaves.

amino groups for thiocyano group-s via the corresponding diazonium salts according to the Sandrneyer method. By this procedure, it is possible to prepare those thiocyano compounds which are accessible only with difficulty by direct substitution, e.g. m-t'hiocyano-anilines.

The following examples show in greater detail the activity of the compounds to be employed according to the invention:

Example 1 The above-mentioned compounds can be employed as herbicides. In the widest sense, the term weeds is applied to plants which grow in places where they are not wanted. They can in addition be employed as desiccants and defoliating agents. Their application is effected with the use of inert carrier material by the spraying sprinkling, or dusting technique. The compounds are also characterised in that they exert a strong phytotoxic activity when sprayed or sprinkled even at low concentrations. Their phytotoxicity varies depending upon the type of the substituents on the ring, so that the compounds can be employed as agents with a selective activity and also as total herbicides.

For the following application, the spray solutions were prepared by dissolving the active agents in acetone and 7 emulsifying them in water with the addition or" an emulsitying agent. Their application is effected with commercial spraying or sprinkling apparatus.

At the time of treatment, the plants had a height of 5-15 cm., depending on the plant variety. The cereal The damage to the plant was evaluated 3 weeks after the treatment. In the following experiments to determine an active amount, the specified indices signify:

0=no effect, 1=slight scorch marks, 2=distinct marginal scorching, 3=severe damage, individual leaves destroyed, 4=plant partially destroyed, 5=plant completely killed.

After spraying the diflerent plant varieties with a 0.1% solution of the following compound:

NC s-QN-(omh the following degrees of damage resulted:

The compound is also suitable for selective weed control in cereals, when the concentration is reduced to 0.01%. After treatment with a 0.01% solution, the following results were obtained:

Panicum spec. 5 Chenopodium album 4-5 Avena sativa 0 Triticum aestivum l Gossypium herbaceum 5 Sinapis arvensz's 5 Stellaria media 4-5 Portulaca oleracea 5 Oryza sativa 0 2. Method for controlling plant growth which comprises applying to a plant an active amount of a compound of the formula OCH Concentra- Compound tion applied, Millet Beet Oats Cotton Wheat Mustard Tomato Bean percent t NECS CHzCHrCHz-OH: 0.2 5 a 5 2 5 5 s 'NECS-NH1 0.2 3 2 a s 3 4-5 2 1 SICH2CH2-OH NEG-S-QNH-Czfi; 0.2 4-5 45 a 4-5 2 45 e5 5 NE os N (OHFCH2 O H), 0. 2 3 2-3 2 2 1-2 4-5 2 1 NEG-SNHCHzCHz-OH; 0.2 5 4-5 3 5 3 5 5 5 Example 2 4. Method for controlling plant growth which com- The compound prises applying to a plant an active amount of a compound of the formula NO s-QN-(cnrm 12115 No S-NC oc11lo1 also acts like the compounds already mentioned above C1 and moreover it is principally suitable for defoliating cotton. 5. Method for controlling plant growth which com- When ripe cotton plants (50% of the capsules open) prises applying to a plant an active amount of a cornhad been sprayed in the open with 0.2 or 0.1% solutions, Pound f the formula 8090% of defoliation could be observed 7 days later. O H In this test, the analogous dimethyl compound 5 NO S-QNC ON(QHa)2 o1 6. Method for controlling plant growth which comprises applying to a plant an active amount of a comound of the formula was also evaluated, when the same effect was observed. P

We claim: 1. Method for controlling plant growth which corn- NCS @NHOONH OH3 prises applying to a plant an active amount of a compound of the formula 01 7. Method for controlling plant growth which comprises applying to a plant an active amount of a compound of the formula 8. A method for controlling plant growth which cornprises contacting the plant With an active amount of a compound of the formula NC S wherein R is a member selected from the group consisting of a hydrogen, lower alkyl carbonyl, chlor-olower alkyl carbonyl, carbamoyl, phenyl carbonyl, carbo lower alkoxy, hydroxy lower alkyl and lower alkyl; R is a member selected from the group consisting of chloro, lower alkyl and. lower alkoxy; and n is an integer of 1-2.

9. Method for controlling plant growth which com- 9 10 prises applying to a plant an active amount of a com- FOREIGN PATENTS Pmmd havmg the immula 1,294,804 6/1962 France.

NC s-QNH-cgi; OTHERREFERENCES 5 Hartzell et al.: Contribution Boyce-Thompson Institute, CH3 V01. 6, 1934, pp. 269 to 277, p. 271 particularly relied References Cited by the Examiner upon 7 UNITED STATES PATENTS LEWIS GOTTS, Primary Examiner.

2,024,098 12/1935 Heckelt 167--30 10 Examiner, 2,203,919 6/1940 Murphy 16722 3,215,519 11/1965 Desmoras et a1. 71-23 J-O-THOMASAssismmExamine 

1. METHOD FOR CONTROLLING PLANT GROWTH WHICH COMPRISES APPLYING TO A PLANT AN ACTIVE AMOUNT OF A COMPOUND OF THE FORMULA 